1912] ' Mann — Parabiosis in Brazilian Ants 37 



on the association of ants belonging to the same genera. The 

 colonies which he examined contained larvae, and these were 

 grouped separately in different parts of the nest. To this associa- 

 tion, where colonies of different species live in the same nest, but 

 in different chambers, and have no other relations with each other, 

 each species foraging for itself, Forel has given the name "para- 

 biosis." In the case of Dolichoderus and Cremastog aster, it would 

 seem that all the advantage must be on the side of the latter, since 

 it shares the nest built by the other and is well protected, without 

 apparently contributing anything in return. 



Among the observed species of Dolichoderus, bispinosus was 

 the only one capable of being at all offensive to man. One species, 

 D. lugens Emery, which was common on the upper Rio Madeira, 

 attempts to defend itself by secreting from the anus a large drop 

 of yellow, oily substance, but this has no effect on the human skin. 

 Dolichoderus debilis var. rufescens hereafter described, attempts to 

 defend its nest, but because of the small size and feeble mandi- 

 bles, it is scarcely capable of repelling a large intruder. 



In August, while collecting along a trail near Camp No. 41 on 

 the Madeira-Mamore Railroad in the State of Matto Grosso, my 

 attention was attracted to a number of small red Dolichoderus. 

 They were moving excitedly about, holding the abdomen up and 

 a little to one side, so that they had a comically asymmetrical 

 appearance. A tree by the trail had been felled, and in a fork of 

 its branches, at what had been a height of approximately forty 

 feet, I found the nest, an earthy structure, ovate in form, about 

 a foot in length and eight inches in diameter. Fine roots of a plant 

 ramified through this nest in all directions in such a manner as to 

 make it quite firm, despite the nature of its component material. 

 When I dug into the structure, numbers of the Dolichoderus 

 rushed out. WTiile collecting these I had a momentary glimpse 

 of another ant, colored similarly to the Dolichoderus, but much 

 larger, and with long legs. It emerged from one chamber and 

 immediately disappeared into another. Hoping to collect this, 

 as well as all phases of the Dolichoderus, I brought to the place 

 a large quinine can, containing a piece of cotton saturated with 

 chloroform, and began to dig and throw into this fragments of the 

 nest. Hereupon numbers of the large ants rushed out, and my 

 hand was severely stung before I realized that two colonies of ants. 



